Color stabilization of fuel oils



Aug. 25, 1953 E. c. DAIGLE COLOR STABILIZATION OF FUEL OILS 2 Sheets-Sheet 1 Filed Nov. T 15, 1950 5.55. 6230 uZw-FEhSQ.

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BY 20%. ATTORNEY OR AGENT Aug. 25, 1953 E. c. DAIGLE 2,650,187

COLOR STABILIZATION 0F FUEL OILS Filed Nov. 15, 1950 Sheets-Sheet 2 Ill FUEL OIL "'6 3 do t: a.

EARL C. DAIGLE INVENTOR.

AT TORNEY OR AGENT Patented Aug. 25, 1953 2,650,187 COLOR STABILIZATION OF FUEL OILS Earl C. Daigle, Beaumont, Tex, assignor to Company, Incorporated, New York, N. Y., a corporation of New York Application November 15, 1950, Serial No. 195,795

Socony-Vacuum Oil 14 Claims.

This invention relates to a process for stabilizing the color of petroleum fractions and more particularly is directed to a method for inhibiting discoloration and sediment formation in distillate type fuel oils upon storage of the same.

Distillate type fuel oils, i. e., petroleum fractions boiling between about 300 F. and about 700 F. should desirably possess good color stability and be substantially free of sediment in order that the tendency of the oil to corrode or plug the burning equipment in which it is to be employed may be reduced to a minimum.

Heating oil fractions may be obtained by distilling either cracked or crude petroleum products. In the past, such fractions were for the most part obtained from crude petroleum. However, with the increasing production of distillate type fuel oils by catalytic cracking, a product has resulted which goes off color and forms sediment during storage. Stabilization of these heating oils is definitely to be desired. 1

It is therefore the main object of the present invention to provide a method for reducing the tendency of distillate type fuel oils to become discolored and contaminated by sediment formation upon storage over extended periods of time.

In accordance with the present invention, it has been discovered that treatment of the other- Wise finished fuel oil with a small quantity of a high molecular weight polyethylene glycol and subsequent separation of the oil from admixture with the glycol treating agent yields a stabilized oil having an appreciably greater resistance to discoloration and sediment formation than the oil in, untreated condition.

The polyethylene glycols contemplated for use in the present process are those which aresubstantially completely water-soluble at temperatures of 20 C. and higher and possess a molecular weight in the range of 600 to 4000 or higher. These glycols ar characterized by having a specific gravity of about 1.0 to 1.25 relative to Water at normal room temperature, a melting point of about 20 to about 55 0., a Saybolt-Universal viscosity of about 60 to about 700 seconds at 210 F. and a flash point of about 420 to about 550 F.

Representative polyethylene glycols having the terials known in the trade as Polyethylene Glycol 600, Carbowax 1-000, Carbowax 1500, and .C'arbowax 4000. The figure present in these designations represents the average molecular weight of the particular compound.

a Saybolt-Universal viscosity of about to seconds at 210 F., and a flash point temperature of about 475 F.

Carbowax 1000 is a soft, waxy solid characterized by a melting point of about 35 to 40 0., a

Saybolt-Universal viscosity of about to 100 seconds at 210 F. and a flash point of about 480 F.

Carbowax 1500 is a solid having the consistency of petrolatum and characterized by a melting point of about 35 to 40 C., a specific gravity of about 1.15, a Saybolt Universal viscosity of about,

60 to seconds at 210 F. and a flash point of about 430 F.

210 F. and a flash point temperature of about 530 F.

of polyethylene glycol of the above-recited characterlstics, the latter behaves as an extractant to sediment formation. since the above-described high molecular maximum quantity of polyethylene glycol emabout 25 per cent by weight of the oil charge.

Larger quantities have been found to impart no additional improvement to the fuel oil undergoing treatment and, indeed, encumber the process by requiring further facilities for effecting recovery of the relatively expensive polyethylene glycol reagent. Accordingly, under the usual contemplated conditions for operation of the instant process, the amount of polyethylene glycol employed will be between about 2 and about per cent by weight of the fuel oil charge. weight ratio of polyethylene glycol to fueloil will thus be between about 0.02 and about 0.2.

The contact between heating oil fraction and polyethylene glycol takes place under temperature and pressure conditions sufiicient to maintain the same in the liquid state, thereby effecting formation of two immiscible phases. The extract phase comprises the major portion of polyethylene glycol employed and contains the deleterious potential sediment and color forming matter which it is desired to remove from, the fuel oil. The product phase contains the fuel oil mixed with a small amount of polyethylene glycol. These two immiscible phases are separated. The polyethylene glycol reagent is then separated from the product phase by waterwashing, distillation, or other feasible means. Likewise, the olyethylene glycol is removed from the extract phase by distillation or other suitable means. from each of the phases may be re-used for treatment of additional quantities of fuel oil stock.

As a practical matter, it is preferred to effect contact between fuel oil and polyethylene glycol reagent at substantially atmospheric pressure and at a temperature above the melting point of the particular glycol reagent used. Generally, the temperature of contact will accordingly be between about 70 F. and about 150 F., although it is to be realized that lower temperatures may permissibly be used with an increase in pressure.

The method of this invention may be carried out either as a batch operation or as a continuous process. Suitable continuous procedures are shown in the attached flow diagrams.

Referring more particularly to the flow diagram of Figure 1, fuel oil stock to be treated is. conducted from tank In through pipe H into mixing tank l2. Likewise, polyethylene glycol re-, agent is led from storage tank l3 through pipe, l4 into mixing tank l2. Thorough agitation of the oil and glycol reagent takes place in this tank. Thereafter, the resulting mixture is conducted through pipe I5 .to settling tank Hi. There, phase separation takes place into an upper layer comprising the oil product and a small quantity of the polyethylene glycol and a lower extract layer comprising the major portion of polyethylene glycol, together with the deleteri- The-- The polyethylene glycol so recovered ous matter which it is desired to remove from the oil. The upper product layer is withdrawn through conduit l1 and led into wash tank I8 where it is washed with water introduced through conduit 19. Since the polyethylene glycol is completely soluble in water while the fuel oil is insoluble therein, an effective separation of fuel oil and polyethylene glycol reagent is accomplished during the water washing. The fuel oil product is withdrawn from the upper portion of tank I8 through pipe 20 while the water solution of polyethylene glycol is withdrawn from the bottom of tank 18 through pipe 21. The aqueous solution of polyethylene glycol is then led into distillation tower 22 where water passes ov rh ad as a vapor and polyethylene glycol is obtained as a bottoms product. The polyethylene glycol so obtained is removed from the bottomof tower 22 and recycled by means of pipe 23' to storage tank 13.

The lower layer contained in settling tank It is withdrawn therefrom through pipe 24 into extract tank 25 from which it is fed into distillation tower 26. The polyethylene glycol contained in such feed mixture is separated as a bottoms product through conduit 21 and is return to storage tank IS. The deleterious sediment and color forming matter removed from the fuel oil passes overhead through outlet pipe 28.

Turning now to the flow diagram of Figure 2, an alternate continuous treating procedure employing counter-current oil stock tobe treated is conducted from tank 30 through pipe 3| into the tower 32. 1 There, theoil flowing upwardly through the tower comes in contact with the downflowing polyethylene glycol introduced into the upper portion of the tower from storage tank 33 through conduit 34. The counter-current flow of polyethylene glycol reagent and oil afiolds an intimate degree of contact between the two streams and thereby permits the deleterious sediment and color forming matter contained in the fuel oil to be removed by the downflowing poly ethylene glycol. A stream of fuel oil so stabilized and containing a small amount of polyethylene glycol is withdrawn tower 32 through pipe 35 andconduct'ed to distillation tower 36 where the" fuel oil product passes overhead while polyethylene glycol collects in the bottom of tower 36 and is withdrawn therefrom through pipe '31 and then returned to storage tank 33. I The polyethylene glycol stream containing the deleterious matter previously removed from the oil is led from the bottom of treating tower 32 through pipe 38 and conducted to distillation tower 39. The polyethylene glycol contained therein is separated as a bottoms product through conduit 40 and is recycled to storage tank '33. The sediment and color forming matter removed from the fuel oil passes overhead through outlet 4!.

The following specific examples will serve toillustrate the results achieved in accordance with the present invention:

Example 1 A heating oil having the'following characteristics:

'Gravity,A.P.I V 32.8 7 Flash point 166 F Pour point 0 F.

Viscosity, Saybolt-Universal (100 F.) 35 sec.

Sulfur content 0.42% Aniline number l36.4 F. Diesel index 44.7 Distillation IBP F 346 10% F 426 50 -F 510 F 58'! E. P. F 638. Rec. per cent 98 was tested for color and found to possessa color of Light 1 on the NPA scale. This oil, after storage for 24 hours at a temperature of 212 F. was contaminated by heavy sediment and upon testing for color was Dark 4 on the NPA scale.

flow is shown. The fuel lower portion of treatin from the upper portion of' found to have a color of ture of 145 F. and at atmospheric pressure for about 1 minute. After contacting, the extract phase comprising Carbowax 4000 and deleterious matter was separated from the oil phase. The oil phase was then water-washed to remove the Carbowax- 4000 contained in the oil and the water was saved for Carbowax recovery. The resulting oil product, upon testing for color, was found to have a NPA color of 1. After storage of this oil for- 24 hours ata temperature of 212 F., the oil was found to contain only a trace of sediment and to have a NPA color of Light 3.

Example 2 A heating oil having the following characteristics:

Gravity, A. P;I 32.4". Flash point .4 160 F. Pour point F. Viscosity, Saybolt-Universal (100F.) 35. sec. Sulfur content 0.59% Aniline number 131.1. Diesel index 42.5. Distillation: I

I. B. P. "1 v 350 10% F 416 50 n, F 510 90 F 593. E. P, F.. 644 Rec. per cent 99 upon testing for color was found to have a NPA color of Light 2. After storage of this oil for 24 hours at 212 F., considerable sediment formed and the color of the oil was 5 on the NPA scale. The same oil was then treated with Carbowax 4000 in the amount of per cent by weight of the oil. Contact was carried out at a temperature of 145 F. and at atmospheric pressure for After contacting, the extract of Light 2 /2 on the NPA scale. After storage of this oil for 24 hours at 212 F., the NPA color was 7' and the oil was contaminated by heavy sediment. V

The same oil was then treated with Carbowax 400 in the amount at 212 F. yielded only a trace of sediment and the oil was found to have a NPA color of Dark 3 20. Viscosity, Saybolt-Universal (l00F.) 35 sec.

Sulfur content 0.97%. Aniline number 123.6 F. Diesel index 36.0. Distillation:

I. B. P F 380 10% F 440 50 F 534 90 F 616 E. P. F 644 R60. per cent 98 was tested for color and found to have a color of 1 on the NPA scale. After storage of this oil for 24 hours at 212 F., the oil was found to have a NPA color of 6 and to be contaminated by heavy sediment formation.

Contact was carried out as in Example 1. The resul ing stabilized oil had a NPA color of 1 and after storage for 24 hours at 212 F., was substantially free of sediment and was characterized by a NPA color of Light 4 Examp e 5 about 1 minute. I

phase comprising ,Carbowax 4000 and sediment and color forming matter was separated from the oil phase. The oil phase was then vacuum-distilled at a maximum temperature of 450 F. and a pressure of 10 mm. of mercury to remove the small amount of Carbowax 4000 contained in the oil. The resulting oil product, upon testing for color, was found to have a NPA color of Dark 1. After storage of this oil for 24 hours at a temperature of 212 F., the oil was found to be substantially free of sediment and to have an im- A sample of the heating oil employed in Example 4 was treated with Carbowax 4000 in the amount of 10 per cent by weight of the oil. Contact was carried out as in Example 4 and the resulting stabilized oilwas stored for 2 months at a temperature of 100 F. At the end of this time, the oil was found to have a NPA color of 4 and to contain 2% mgs. of sediment per 100 ml. of oil. The unstabilized oil, after storage for 2 months at 100 F, was found to have a NPA color of Dark 7 and to contain 14 mgs. of

proved color 2% on the NPA scale. sediment per m1. of oil.

Example .3, Ewanmle 6 A heating il having the followin ha t A heating oil having the following characteristics: istics:

60 o Gravity, A. P. I. 30.0". ra I..- 29.1- Flash point F. Flash pom F. Pourpoint 15 P ur P0 11 V 20 Viscosity, sayboltrUniversa-l (100 Vi cosity. savbolt um ersal (100. F.) 3556 Sulfur content Aniline number h Diesel index e 37.0. Distillation:

Sulfur content ni ine number Diesel index, l.. 36.0

Distillation:

upon testing was found to have. a NPA color of 600 and deleterious matter was separated from the oil phase. 'The oil phase was then waterwashed to remove the small amount of Polyethylene Glycol 600 contained therein and the water was saved for recovery of the polyethylene glycol.

for color, was found to have a NPA color of 2. After storage of this oil for 24 hours at a temperature of 212 F., only slight sediment formation was found to occur and the oil was found to have a NPA color of Dark 4 /2.

Example 7 A sample of the oil employed in Example 6 was treated with 20 per cent by weight of Polyethylene Glycol 600 at a temperature of 105 F. and atmospheric pressure. Contact was thereafter carried out as in Example 6 and the resulting oil product was found to have a NPA color of 2. After storage of this stabilized oil for 24 hours at a temperature of 212 F., the oil was found to contain only a trace of sediment and to have a NPA color of Light 4.

Example 8 Example 9 A sample of the oil employed in Example 6 was treated with 10 per cent by weight of Pol ethylene Glycol 600 at a temperatureof 145 F. and atmospheric pressure. Contact was otherwise carried out as in Example 6. The resulting oilproduct was found to have a NPAcolor of 2. After storage of this oil for 24 hours at .a

temperature of 212 F., the NPA color was 4 /2 Example 10 A sample of the oil employed in Example 6 was treated with Carbowax 1000 in the amount of per cent by weight of the oil. Contact was carried out at a temperature of 120 F. and at atmospheric pressure for about lminute. contacting, the extract phase, comprising Carbowax 1000 and the sediment and color forming matter removed from the oil, was separated from the oil phase. The oil phase was then waterwashed to remove the small amount of Carbowax 1000 contained therein and the water saved for Carbowax recovery. The resulting oil product, upon testing for color, was found to have a NPA color of Light 2 /2. After'storage of this oil for 24 hours at a temperature of 212 F., the oil was found to have a NPA color of Dark 4 /2.

From the foregoing examples, it will be evident that a distillate type fuel oil treated with a polyethylene glycol reagent in accordance with After" The resulting oil produchupon testing 8' i the method ,described herein, affords an effective method for inhibiting sediment formation and stabilizing the 'oil, against discoloration during storage. 1 The process of this invention as indicated here- I inabove may be carried out either as a batch operation or as a continuous method employing concurrent or counter-current flow of polyethylene glycol reagent and the fuel oil undergoing treatment. It is also contemplated that a mixture of polyethylene glycol and water may under certain conditions be used for removing the deleterious mattercontained in the fuel oil which gives rise to heavy sediment formation and discoloration of. the oil'during storage.

It is to be understood that the above description is merely illustrative of preferred embodiments of the invention, of which many variations may be made within the scope of thefollowing claims by those skilled in the art without departing from the spirit thereof.

Iclaim: l. A method for reducing sedimentation and stabilizing the color of a distillate'typesfuel .oil

boiling between about 300 F. and about 700 F.

and subject to sediment formation and discoloration upon storage, which comprises liquid phase contacting of said oil with a polyethylene glycol characterized by a molecular weight of at least about 600 and substantially complete solubility in water, the amount of said polyethylene glycol present being not less than about 2 per cent and not more than about 25per cent by weight of the oil, forming immiscible phases comprising an oil layer mixed :with :a small amount of said polyethylene glycol and a second layer comprising the bulk of said polyethylene glycol together with deleterious matter removed fromrsaid oil, separating said immiscible phases and recovering oil of 7 improved sedimentation and color stability from said oil layer. a r

2. A method for reducing sedimentation and stabilizing the color of a .distillate type fuel oil boiling between about 300 F. and about 700 F. and subject to sediment formation and discoloration upon-storage, which comprises liquid phase contacting of said oil with a polyethylene glycol ing the bulk of said polyethylene glycol together with deleterious matter removed from said oil, separating said immisciblephases and recovering oil of improved sedimentation and color stability from said oil layer. r

3.- A method for removing deleterious sediment and color forming matter from a distillate type fuel oil boiling between about 300 F. and about 700 F., which comprises extracting sai'd matter from said oil with a small amount 'of a high molecular weight polyethylene glycol at a temperature and'pressure sufficient to maintain the same in the liquid state, the molecular weight of said polyethylene glycol beingbetween about 600 and 4000 and-the weight ratio of polyethylene glycol to fueloil being between about 0.02 and about 0.2, whereby two immiscible layers are formed, oneof whichjcomprises the oil mixed with a small amount of said polyethylene glycol and the second of which comprises the .bulk of said polyethylene glycol togetherwith deleterious matter removed from said .00, separating said immiscible layers and recovering an oil of improved sediment formingtendenciesand improved color stability. t

4. A method for removing deleterious sediment and color forming matter from a distillate type fuel oil boiling between .300" F. and 700 which comprises extracting said matter from said oil with a high molecular weight polyethylene glycol at a temperature and pressure sufiicient tomaintain the same in glycol being characterized byan average molecular weight of about fiflo, afreezing ,pointof about t .20 to 25 (3., a specific gravity of about.1.13 and a c -onds at 210 F., the weight ratio of said polyethylene glycol to fuel oil being between about 0.02 and'about 0.2, wherebyltwo immiscible layers are formed, one of which comprises the oil mixed with a small amount of said polyethyleneglycol and the second of which comprises the bulk of said polyethylene glycol together with deleterious matter removed from said proved color stability.

5. A method for removing deleterious-sediment and color forming matter from a distillate type .fuel oil boiling between 300 F. and 700 F., which comprises extracting said matter from said oil witha high: molecular weight polyethylene glycol at a temperature and pressure sufficient to main- 40 ,C. and a Saybolt-Universal viscosity of about 80 to 100seconds at;2l-0;F.,.the weight ratioof :said polyethylene glycoltofuel oil. being between proved sediment forming-tendencies and improved 60101 stability.

6. A method for removingdeleterioussediment and 'color forming matte from;.a distillate type and..color forming matter from a distillate type a liquid state, said polyethylene Saybolt-Universal viscosity of about 60170 secremoving deleterious sediment stabilizing :the .color of .a

ular weight of 4000, a melting point of about to C., a specific gravity of about 1.20, and a Saybolt-Universal viscosity of about 500 to 700 seconds at 210 F., the weight ratio of said polyethylene glycol to fuel .oil being between about 0.02 and about 0.2, whereby two immiscible layers are formed, one of which comprises the .oil mi-xed with a small mount of said polyethylene glycol and the second of which comprises the bulk of said polyethylene glycol together with deleterious matter removed from said oh, separating said immiscible layers and recovering a n oil of improved sediment fo m tend ncie and improved colorstability.

8,. A method for removing deleterious sediment and color forming matter from a distillate type fuel oil boiling between 300 F. and 700 E, which matter from said oil the weight ratio of said 7 V fuel oil being between about 0.02 and about 0.2, whereby two immiscible layers areformed one ethylene glycol togetherwith deleterious matter removed fromsaid OiLseparating saidimmiseible layers and recovering .an vnil ,of improyed t sediment forming tendencies and improved color stability.

:9. A method for reducing sedimfil iation and disti late t p e .o boiling between about 300.F. and about 700 F. and subject tosediment formation and discoloramp ise 7 co t c n and about 150 F. :withca polyethylene glycol characterized bya molecular .weight of at least about 600 t and substantially pomplete solubility in water, the .amount of said polyethylene glycol present being not less 1than1about2 per cent and not more than about 2 5.;per, cent by w i ht (of the oil, forming immiscible phases comprising an ioilxlayerimixeduwith.a small amount of said poly- --ethylene glycol and. a second layer comprising the bulk of said polyethylene.glycolto e lher with deleterious matter removed from said oil, separating said immiscible phases and recovering oil of improved sedimentation and color stability from said oil layer.

10. A continuous process for reducing sediment formation and eifec'ting color stabilization of a distillate type fuel oil boiling between about 800 F. and about 700 F., which comprises continuously contacting said oil with a polyethylene glycol of 600 to 4000 molecular weight at a temperature suilicient to insure a liquid phase contact, the amount of said polyethylene glycol being greater than about 2 per cent but less than about 25 per cent by weight of the 011,, continuously forming two immiscible phases comprising a lower layer of polyethylene glycol containing deleterious matter extracted from said oil and an overlying layer of oil mixed with a small amount of polyethylene glycol, continuously withdrawing a stream of said overlying oil layer, continuously separating polyethylene glycol from said stream to yield a fuel oilof improved sediment forming tendencies and improved color stability and recycling said separated polyethylene glycol to contact with a fresh supply of the oil undergoing treatment.

' tinuously contacting said oil with a polyethylene glycol of 600 to 4000 molecular weight at a temperature sufiicient to insure a liquid phase, contact, the amount of said polyethylene glycol being greater than about 2 per cent but less than about 25 per cent by weight of the oil, continuously forming two immiscible phases comprising a lower layer of polyethylene glycol containing deleterious matter extracted from said oil and an overlying layer of oil mixed with a small amount of polyethylene glycol, I continuously withdrawing'a stream of said overlying oil layer, continuously washing polyethylene glycol from said stream with water to yield a fuel oil of improved sediment forming tendencies and improved color stability, separating the resulting aqueous solution into water and polyethylene glycol and recycling the polyethylene glycol so separated to contact with a fresh supply of the oil undergoing treatment. a

12. A continuous process for reducing sediment formation and effecting color stabilization of a distillate type fuel oil boiling between about 300 F. and about'700 F., which comprises continuously contacting said oil with a polyethylene glycol of 600 to 4000 molecular weight at a temperature sufficient to insure a liquid phase contact, the amount of said polyethylene glycol being greater than about 2 per cent but less than about 25 per cent by weight of the oil, continuously forming two immiscible phases comprising a lower layer of-polyethylene glycol containing deleterious matter extracted from said oil and. an overlying layer of oil mixed with a small amount of polyethylene glycol, continuously withdrawing a stream of said overlying oil layer, continuously distilling oil from said stream to yield a fuel oil-of improved sediment forming tendencies and improved color stability and recycling the polyethylene glycol soseparated to contact with a fresh supply of the oil undergoing treatment.

13. A continuous process for reducing sediment formation and effecting color stabilization of a distillate type fuel oil boiling between about 1 300 andjabout 700 E, which comprisesco'ntinuously countercurrently contacting said oil with a polyethylene glycol of 600 to 4000'molecular weight at a temperature 'between' about 70 F. and about 150 F.,'the weight ratio ofsaid polyethylene glycol tofuel oil being between about 0.02 and about 0.2, continuously forming two immiscible phases compris'ng a lower layer of polyethylene glycol containing deleterious matter extracted from said oil and an overlying layer of oil mixed witha small amount of polyethylene glycol, continuously withdrawing 'a stream, of

said overlying oil layer, continuously separating polyethylene glycol from said stream to yield a fuel oil of improved sediment forming tendencies and improved color stability and recycling said separated polyethylene glycol to contact 7 with a fresh supply of the oil undergoing treatamount of polyethylene glycol,

withdrawing a stream of said lower layer, sep

ment. V

'14. A continuous 'process for reducing 'sedie ment formation and effecting color stabilization of a distillate type fuel oil boiling between about 300 F. and about 700 E, which comprises continuously contacting said oil with a polyethylene glycol of 600 to 4000 molecular weight at a temperature sufficient to insure a liquid phase contact, the amount of said' polyethylene glycol being greater than about 2 per cent but less than about 25 per cent by weight of the oil, continuously forming two immiscible phases comprising a lower layer of poly'ethyleneglycol containing deleterious matter extracted. from said oil and an overlying layer of oil mixed with a small continuously arating polyethylene glycol therefrom and recycling .said separated polyethylene glycolto contact witha fresh supply of the oil, continu ously withdrawing'a stream of said overlying oil layer, continuously separating polyethylene glycol from said stream to yield a fuel oil of improved sediment forming tendencies and improved color stability and recycling said sep arated polyethylene glycol to contact with a fresh supply of the oil undergoing treatment.

EARL c. DAIGLE.

References Cited in the file of this-patent UNITED STATES PATENTS 2,514,997 ,1 Floyd July 11, 1950 

1. A METHOD FOR REDUCING SEDIMENTATION AND STABILIZING THE COLOR OF A DISTILLATE TYPE FUEL OIL BOILING BETWEEN ABOUT 300* F. AND ABOUT 700* F. AND SUBJECT TO SEDIMENT FORMATION AND DISCOLORATION UPON STORAGE, WHICH COMPRISES LIQUID PHASE CONTACTING OF SAID OIL WITH A POLYETHYLENE GLYCOL CHARACTERIZED BY A MOLECULAR WEIGHT OF AT LEAST ABOUT 600 AND SUBSTANTIALLY COMPLETE SOLUBILITY IN WATER, THE AMOUNT OF SAID POLYETHYLENE GLYCOL PRESENT BEING NOT LESS THAN ABOUT 2 PER CENT AND NOT MORE THAN ABOUT 25 PER CENT BY WEIGHT OF THE OIL, FORMING IMMISCIBLE PHASES COMPRISING AN OIL LAYER MIXED WITH A SMALL AMOUNT OF SAID POLYETHYLENE GLYCOL AND A SECOND LAYER COMPRISING THE BULK OF SAID POLYETHYLENE GLYCOL TOGETHER WITH DELETERIOUS MATTER REMOVED FROM SAID OIL, SEPARATING SAID IMMISCIBLE PHASE AND RECOVERING OIL OF IMPROVED SEDIMENTATION AND COLOR STABILITY FROM SAID OIL LAYER. 